Whiteout
by goodbye2pisces
Summary: A seemingly deserted ice planet conceals a deadly secret that proves especially dangerous for the Doctor, but could Donna hold the key to saving his life?
1. Chapter 1

_Torchwood_

Martha is sat alone at her desk when she hears it, the familiar whining thrum of the TARDIS, her engines grinding and wheezing as she approaches. A wind picks up from nowhere, rifling through the stacks of files piled high on the edge of Martha's desk.

"Jack!" she cries, looking up to catch his eye through the glass partition separating their offices.

"I hear it," he says, both of them scrambling out of their chairs. They grin excitedly at each other, clasping hands as they emerge onto the central platform.

Neither one of them has seen or heard from the Doctor in nearly ten months, the last word, relayed by Wilf, that he'd showed up out of the blue last October to restore Donna's memories, then promptly disappeared with her again.

"First I'll give him a hug, then I'll give him a slap for disappearing for so long without a word," Martha says, only half-jokingly.

Jack's expression turns thoughtful, his head tilted slightly to one side, "Does she sound strange to you?" he asks.

Martha's grin falters as she listens, a note of discord underlying the otherwise familiar tone. "Now that you mention it," she says at the exact moment the TARDIS blinks into existence several feet above their heads, almost as if she's been expelled against her will from the time vortex.

"Incoming!" Jack shouts, pulling Martha to the ground as the TARDIS spins out of control above their heads, crashing into the tiled wall above the couch and bouncing off like a giant pinball in a shower of hot sparks.

Martha yelps, and she and Jack flatten themselves against the ground when the TARDIS spins back towards them. She barely clears their prone bodies before crashing into the steel railing above the medical bay.

She skids along it with a bone jarring scrape that sets Martha's teeth on edge, then reels backward for just a moment before finally coming to a shuddering halt on the very edge of the landing.

Jack and Martha lay panting for a moment, leftover adrenaline coursing through their veins. They stare at the battered blue box, the closed front door marred by three deep slashes discolouring the blue stained wood.

"What…" Jack mutters, his eyes straying to Martha's face.

She shakes her head, staring at the still closed doors with growing concern.

"You'd better…" she mutters.

"Yeah…" Jack says, rising to his feet. He reaches into his pocket for the plain Yale lock key hanging from the silver chain that he's never without.

The doors fly open just as he reaches the threshold, a highly distraught Donna stood in the smoke-filled doorway propping up a pale, trembling Doctor. Donna's face is caked with dried blood from some unseen wound at her hairline and she's covered in grime.

"Jack!" she cries, cradling the Doctor's clammy face in her mitten covered hand. They're both wearing bright orange snow suits, though the Doctor's anorak is missing. His thick cable knit pullover and bibbed overalls are covered in the same sooty grey grime as Donna's. "Help me!"

"What is it?" Martha cries, grabbing her medical kit as she rushes forward to help Jack ease the Doctor's trembling body to the floor.

"M...Martha," the Doctor gasps, his eyes screwed shut as he writhes fitfully on the floor. His breath explodes in short ragged bursts, "c...can't…" he groans.

"It's all my fault," Donna cries, tears running down her grubby face. She tears off her mittens, her trembling fingers reaching out to him. "I made him go."

"Made him go where?" Martha demands, eyeing the dozens of subcutaneous bruises standing out over his face and body. "Donna, what's happened to him?!"

Donna licks her lips, swallowing convulsively. She looks ill, as if she's about to be sick. It might be the head wound Martha thinks, but she also notices that Donna's put on weight. It's apparent in her face and in her hips and in the heavy coat that's stretched snugly across her midsection. Martha's eyes widen slightly. If she didn't know better, she'd swear Donna was…

"There was a distress signal," Donna says, recapturing Martha's attention. Tiny beads of sweat stand out all over her face. "It was barely functioning. The Doctor said it had been transmitting for decades. It was probably too late to help whoever had sent it."

"But you stopped anyway, yeah?" Martha says and Donna nods.

"I convinced him. I knew he'd regret it if we didn't," Donna says, here voice catching with unshed tears, "but I was wrong."

The Doctor groans, his breathing growing more laboured. Martha tears her eyes away from Donna to see his eyelids slide shut, his back arching in pain. "Run… running out… of… time," he gasps, barely able to force the words out. His eyes are shot through with broken blood vessels. Involuntary tears slowly seep from them, trickling down his face into his hair. "Can't… can't… regenerate."

"What's he mean?" Jack demands, his voice rising sharply.

The tears are tinged pink with blood. As Martha watches the Doctor's skin begins to change. The bruises discolouring it seem to meld together like oil on the surface of a puddle as it grows darker and less pliable, almost like the exoskeleton of an insect.

"What the hell…" she breathes.

"Oh God," Donna gasps horrified, her pale face turning ashen as she desperately grips Martha's arm. "It's started, he's changing," she babbles anxiously, "You have to stop it Martha!" she cries, "please, you have to stop it before it's too late!"

"What do you mean changing?" Jack demands. "Changing how?" The Doctor shudders, the dark irises of his eyes expanding into glinting blackness.

"We need to get him down to the medical bay," Martha says, her eyes straying to Jack's face.

"N… no," the Doctor gasps, his trembling fingers scrabbling at Jack's sleeve as Jack prepares to lift him over his shoulder, "cry… cryo…"

"What, cryofreeze?" Jack asks, his brow knitting in concern at the sight of the Doctor's blackened fingertips poking out from the tips of his cutoff gloves.

"But that didn't work," Donna desperately reminds him, "back on the planet. It didn't work."

The Doctor nods rapidly, wine coloured tears seeping from his eyes. "N… no," he says, "buy… some time… s… slow… down the… process… p… please… Mar...Martha..."

"We can feed the readings from the cold storage chambers directly to the medical bay," Martha agrees with a terse nod. "I should be able to find out what's going on from there."

There's a sickening sort of wet popping sound and the Doctor suddenly screams, his body convulsing as his bones begin to shift and crack, literally reshaping themselves under his skin. His arms and legs begin to stretch, slowly elongating before their horrified eyes. His fingers expand like knitting needles, growing in length, his fingernails blackened and sharp looking and dripping viscous fluid.

"Christ!" Jack cries.

"Do it, Jack, go!" Martha shrieks, steadying Donna as she doubles over suddenly, gagging dryly over the platform railing. "Get him down there now!"

Jack grabs the screaming Time Lord and slings him over his shoulder, running like the clappers for the stairs at the far end of the platform.

"Stay here," Martha tells Donna, taking off after Jack. She isn't surprised when Donna ignores her and follows a few moments later.

They both pelt down the stairs after Jack, emerging into a narrow hallway lined with tiny cells on either side. The alien occupants inside stare at them from behind thick plexiglass walls as they fly past.

Another staircase and they fly down that one as well, emerging into a wider corridor with brick walls and a high cathedral ceiling. The track lighting overhead gives way to hanging ceiling lamps inside the huge round cold storage chamber at the end of the hall. Dozens of small metal doors are built into the walls, stacked one on top of the other.

"I can't," Donna suddenly gasps, balking at the entryway to the morgue-like chamber. "I can't go in there." She turns away, panting heavily, her back pressed to the wall beside the arching entryway.

Martha stays with her, watching Jack from beneath the arch as he pulls out a chamber drawer and quickly deposits the Doctor's writhing body into it, his wheezing screams beginning to change pitch, becoming lower and more guttural.

Jack hits a sequence of buttons on the side of the chamber, sliding the drawer back into the wall, but just before it closes, the Doctor grabs him by the front of his shirt and pulls him down towards him. He gasps something into Jack's ear before dissolving once more into incoherent screams, his back arching amid a flurry of wet sounding pops.

Jack grimaces, his hands shaking slightly as he slams the drawer shut, panting against it until the Doctor's screams abruptly cut off a moment later. Donna slides down the wall, sitting heavily on the floor, her long legs splayed out before her. One hand covers her mouth as sloppy tears run down her cheeks.

Martha stands there a moment longer to watch Jack slowly straighten his shirt, before she goes to her.

"Is there anything I can get for you," Martha asks, kneeling beside her. She gives Donna's shoulder a sympathetic squeeze. "A glass of water? ...Saltines?"

Donna looks up sharply at that. "I'm fine," she murmurs.

Martha nods. "Seriously though," she says, not unkindly, "you should try to eat something. It'll help with the morning sickness."

Donna sniffs and swallows, saying nothing. Sluggish tears roll down her face as she slowly heaves a long shuddering sigh. "I could use a tissue," she says at last, "the Doctor he…," she falters for a moment, her breath catching in a sudden sob, "he carries them in his pockets in those little plastic packages," she says, nearly smiling through her tears. "Seems like I start blubbering at the drop of a hat these days," she shrugs, "hormones I guess."

Martha smiles, gently rubbing Donna's arm. Donna swipes the tears from her eyes as if embarrassed by them. "It's not morning sickness," she says, pulling herself together with some effort, "it's the smell in here, which I suppose _is_ morning sickness technically so forget what I just said."

"You're pregnant?" Jack asks sharply, emerging from the cold storage chamber just in time to catch the tail end of the conversation, his eyes tracking the length of Donna's body before coming to rest on her widening midsection.

"If I had to guess, I'd say about six-months, yeah?" Martha asks.

"Twenty-one weeks," Donna confirms, her eyes dropping to the floor. "We didn't... We weren't..." she stammers, swallowing the last of her tears, "I mean, it wasn't planned or anything. It just sort of… happened."

" _Who_ didn't plan _what_?" Jack demands, looking as if his eyeballs are about to pop out of his head. "Who's the father?"

"Who d'ya _think_ Jack?" Martha snaps at him.

Jack's eyebrows shoot up, his eyes falling on Donna's flushed face. She shrugs slightly in embarrassment. "No!" he says breaking into a sudden incredulous grin. He glances over his shoulder into the cold storage chamber. "That dog!"

Martha and Donna exchange an eye-rolling glance.

"I _knew_ all that lofty speak about Time Lords evolving _beyond_ such things was just a load of gas," Jack continues gleefully, "I wish I could've seen the look on his face when he finally had to admit that he's just as carnal as the rest of us."

"Later Jack," Martha absently scolds him. "We need to get back up to the medical bay. Did you set the feed?" she asks.

Jack nods. "The Cryo-chamber's readings are accessible through the main monitor in the medical bay as ordered," he says.

"Good," Martha says, her eyes returning to Donna's face, "that head needs seeing to," she says, indicating the wound creasing Donna's scalp with a tilt of her chin.

"I'm all right," Donna says softly, undoing the zip on her anorak and wearily running her finger along the inside collar of her thick pullover, her belly round and padding the heavy fabric of her overalls.

"Let me be the judge of that," Martha says gently.

Donna just looks at her. "Shutting him up in that drawer," she says, her voice cracking raggedly, "it won't help. He'll still change."

Martha glances up at Jack, his expression grim, "The Doctor seemed to think it would buy us enough time to reverse whatever's happening to him," she says, trying to sound encouraging.

"Can you?" Donna asks, her eyes flickering anxiously between Jack and Martha's faces, "can you reverse it?"

"I can't really say, Donna," Martha says truthfully, squeezing Donna's hand, "not until we get back to the medical bay and I can get some idea of what we're up against."

Donna swallows, her eyes filling with tears.

"I'll know more after I've run some tests," Martha continues, "but in the mean time, knowing what happened might shed some light on his condition."

"I'm not really sure I even know where to start," Donna says, angrily swiping the tears from her eyes with her fingertips.

"Start at the beginning," Jack says with an encouraging smile. He helps Donna to her feet and hands her the handkerchief from his breast pocket.

Donna returns the smile somewhat wanly, dabbing at the corner of her eye. Her other hand absently rubs her belly as she slowly nods. She sniffs and takes a deep breath, as if steeling herself.

"Right well, like I said," she begins solemnly, "there was a distress signal."

 _Twelve hours earlier_

The Doctor emerges from the TARDIS inside an underground base of some kind. It's dark and eerily quiet, save for the relentless hurricane winds howling furiously some miles above on the planet's surface. There's no atmosphere to speak of. He briefly adjusts the settings on the sonic and finds the air is composed mostly of Nitrogen gas with traces of Methane and Carbon Monoxide thrown in for good measure. He'll be able to hold out for a while thanks to respiratory bypass, but there's no way any human could survive here for more than a few minutes.

It's frigidly cold. Even inside his heavy snowsuit, he's visibly trembling. He brushes the inside collar of his anorak with his fingers, already stiff with cold despite his thick wool cutoff gloves. He activates the environmental field built into the suit. A low whine fills his ears as the field expands to cover his body, then settles into a barely noticeable background hum. The Doctor relaxes slightly as relative warmth suffuses his body.

He fumbles inside his coat pocket for a moment and produces a compact torch to cut through the gloom. The base is no more than a series of roughly hewn tunnels intermingling with the natural caverns that already exist beneath the ice planet's surface.

He scans the arched ceiling with the torch to find neat rows of tract lighting nestled amongst the sawed off stalactites, dark and murky with disuse. Heavy mining equipment sits neglected in hollowed out alcoves carved into the walls, glittering in the torch beam beneath a thick layer of ice crystals. Whatever happened here, it seems as if the base has been abandoned for some time.

A frigid wind springs up from nowhere, straining the suit's environmental systems to the max and cutting through the Doctor like a knife. The deserted tunnels howl eerily with an echoing banshee like roar. A breach somewhere in the perimeter of the base he guesses, allowing a bit of the perpetual blizzard raging on the surface to find its way underground.

Dense white ice crystals crunch beneath his feet as he cautiously moves further along the murky tunnel. The torch beam strays across a burnt out mosaic of computer consoles obscured beneath a glinting layer of permafrost just up ahead.

"Ah-ha," the Doctor murmurs, nimbly tossing the sonic in his other hand as he approaches it.

"Did you find something?" A voice calls, as the TARDIS doors swing open with a familiar creak a short distance down the tunnel.

"Donna, don't come out here," he warns, turning slightly to shout over his shoulder, "it's dangerous!"

"Oh, right, dangerous," she says with a frown. At least he thinks she's frowning, he can't really make out her face in the gloom. "Good thing you reminded me, or I might have forgotten the other nine thousand times you mentioned it."

The Doctor smiles slightly, rolling his eyes as he bends to remove an access panel at the base of the sprawling mainframe in front of him.

"You said I'd be safe as long as I stayed inside the forcefield." she reminds him.

"See that you do," he says, slipping his glasses on and squinting into the mass of frozen circuitry beneath the console, "or you'll be flopping about on the ground like a fish out of water."

"You sound funny," she says, a note of concern slipping into her voice.

"There's very little oxygen out here," he says absently, frowning at the mass of frosted over wireless interfaces and computer components inside the dead mainframe. He changes a setting on the sonic and sets to work on the freezer burned system. "I'm trying to reestablish the environmental systems now."

"It can't be good for you either, breathing the air out there," she says.

"I'm not," he says simply, flexing the frigid tips of his fingers to get the blood circulating.

He comes across the distress beacon that led them here, flashing an erratic intermittent signal into the depths of space. According to the time stamp on the central processor, it's been transmitting for just over thirty years.

The Doctor stares at it for a moment, his brow creasing into a troubled frown. It seems unlikely that whoever activated the beacon could have survived for very long under these conditions. He kills the signal with a terse flick of his finger and moves on.

"That's odd," he says, squinting at the system readings scrolling across the flickering monitors after he reestablishes power to the console.

"What is?" Donna asks.

"It looks as if the oxygen converters were deliberately taken offline," he murmurs, mostly to himself.

"Maybe they were performing maintenance on them, or something," Donna says.

"Maybe," he murmurs, a vague uneasiness growing in the pit of his stomach. He shrugs it off. "Oh well," he says, reinitialising the converters with a quick turn of a dial.

The environmental systems sputter back to life with a cough and settle into a quiet droning hum as the converters finally return to the task they were designed for, changing the inhospitable air into something breathable.

As oxygen begins to mingle with the other gases in the atmosphere, the tract lights carved into the ceiling flicker on one by one, illuminating the cavern in an anaemic fluorescent glow. The Doctor wrinkles his nose at them, returning to the console and the data scrolling across the jittery monitors.

The extreme cold has taken its toll on the long dormant systems. He estimates only a few hours of life left in the neglected condensers before they fail for good. Even now they're running at half capacity, converting atmospheric gases into oxygen at a rate of about 18% parts per million, resulting in breathable, but extremely thin air. Sour, too, he thinks, grimacing distastefully, as he takes in a few tentative breaths.

He really doesn't want Donna or the baby breathing this soup in, but he also knows that no force in the universe will keep her from doing exactly as she pleases once she's made her mind up to do it. He smiles slightly at the thought, that passionate nature being one of the things he loves most about her after all.

Still, good sense dictates that he return to the TARDIS and leave this place without so much as a backward glance. Unfortunately, good sense has never been his strong suit; and Donna would never forgive him if they just took off without at least attempting to find survivors, no matter how unlikely their presence.

He sighs and throws her a thoughtful glance over his shoulder as she stands in the open doorway of the TARDIS, protected from the extreme cold inside her environmentally enhanced snow suit. Her expanding belly round and swollen and beginning to strain against the bibbed overalls beneath it.

"I'm coming out there," she says flatly, her eyes narrowing slightly at the doubtful look on his face.

"Yeah, all right," he says, bowing to the inevitable, "but just let me do one thing first."

The last time he wore this snow suit he was the second man on a "one man" walking expedition to the arctic circle. It's a bit roomier now, the bibbed overalls hanging somewhat loosely over his thick wool jumper, but he seems to recall keeping the pockets well stocked with useful survival gear.

He's fairly certain he's got a portable oxygen regulator on him somewhere. Of course he used to have two, but Sir Walter Herbert made off with it when he wasn't looking. Cheeky bloke that Wally, the first man to walk undisputed to the North Pole indeed, but only because the Doctor had carried him on his back for the entire last kilometre.

He finds what he's looking for, a device that looks like a thin leather choker attached to an oblong multifaceted blue gem.

"Put this on," he says, stepping over the TARDIS threshold and handing it to Donna.

"Not exactly my style," she says, pulling a face, but taking the necklace from him anyway. "Now what?" she asks, after fastening it by the clasp at the back of her neck.

The Doctor brushes the gem with his cool fingertips and a tingling field of energy leaps out of it, expanding to cover Donna's nose and mouth in a form fitting invisible shield. She gasps in surprise at the unexpected sensation, staggering and nearly losing her footing before the Doctor steps in and steadies her with a strong arm around her shoulder.

"Give a girl some warning!" she cries tartly, swatting him on the arm.

"Sorry," he grins. He'd kiss her if it weren't for the virtual mask covering her face. His grin turns suddenly cheeky and he abruptly dips her in his arms before returning her to her feet.

"Do that again and I may just throw up on your shoes," she says, smiling slightly as she readjusts her rumpled anorak.

His smile turns a bit sheepish at that. "Right, sorry," he says. She hasn't had a bout of morning sickness for a few weeks now, not since properly settling into her second trimester, but she's still extremely sensitive to strong odours and changes in equilibrium.

"What is this," she asks, tentatively brushing the force field covering her face, "an oxygen mask?"

He nods. "The air out there is just barely breathable," he says. "I'd feel better knowing you were wearing it."

"What about you?" Donna asks, " _barely breathable_ doesn't sound too healthy for you either."

"I've only got the one mask," he says, his eyes momentarily flashing with annoyance, "it's fine though. I'll make do."

"No but, you've got two hearts," Donna says thoughtfully, "wouldn't that mean you'd need more oxygen, not less?"

"Actually, it means that my body is far more efficient at utilising it than yours is," he says simply, "I'll be fine, as long as we don't linger too long." He smiles slightly at the doubtful look on her face and kisses her on the forehead. "Don't worry Donna," he says, "I'm not interested in throwing my life away." He pulls her into a gentle embrace, one hand coming to rest on her growing belly, "I've got too much to live for now."

Donna returns the smile and snuggles against him, but there's something else in her eyes as well, a growing uneasiness that he's been noticing with more frequency lately. It's entirely possible that it has nothing at all to do with his complicating their already complicated relationship by unexpectedly knocking her up just a few months after reuniting with her, but somehow he doubts it.

He knows there's a conversation waiting there, but it'll have to wait a bit longer. He sighs a bit guiltily and brushes the inside collar of her anorak with his fingertips to activate the environmental systems inside her suit.

"Let's go, Mum," he says, taking her mitten-covered hand and leading them back out into the seemingly deserted base.

A swirling wind erupts out of nowhere, kicking up chunks of ice and pelting them with frozen shards that feel like bitter needles pricking their skin. Donna shivers, "Oh my God," she gasps, screwing her eyes shut against the bone jarring cold.

The Doctor immediately steps in front of her to shield her from the worst of the wind with his body. "Yeah," he agrees, "kind of makes the Ood Sphere feel like a day at the beach doesn't it."

"It's shattering," Donna gasps, "why would anyone in their right mind come out here? I mean, what were they _thinking_?"

"Oh well, you know humans," the Doctor says mildly, "indomitable spirit and all that."

"You're loving this aren't you," Donna says, the corners of her mouth quirking into an incredulous smile.

"Well, I wouldn't say _loving_ exactly," the Doctor says thoughtfully, "but I do enjoy a good mystery. Admit it," he says, tilting her chin with his finger, "You do too."

Donna's smile broadens as she squints in the dim glow of the sputtering tract lighting above their heads, taking in the deep spiralling tunnels and long abandoned equipment. "What, were they mining diamonds, or something?" she asks.

"Or, something," the Doctor murmurs mostly to himself. "Come on," he says, taking Donna's hand and setting a brisk pace into the shadowy recesses of the seemingly deserted base.

Three tunnels loom ahead of them, the wind howling eerily along their roughly carved walls. The Doctor stops for a moment to consider their options. The right tunnel curves out at a slightly upward angle. The left turns sharply, then seems to break off into a series of smaller access tunnels. Some sort of natural ventilation system perhaps, designed to distribute the oxygen converted air more quickly throughout the base. The central tunnel is wider than the others and goes straight down.

"Door number two I think," he says, indicating the central tunnel with a nod of his head.

"Why _that_ one?" Donna asks.

"Straight paths tend to lead directly _to_ something," the Doctor says, "plus it's heading down. If you were designing some sort of common living space say, you'd want to conserve heat by carving it deep. It seems the most likely place to find survivors."

"Do you think we will," Donna asks, "find survivors?"

He shrugs. "Anything's possible," he lies, "humans are very resourceful after all."

Donna smiles slightly at that. "What's the year?" she asks, as they step over the chunks of broken ice that litter the entryway at the mouth of the tunnel, the Doctor's hand wrapped solidly in hers to make sure she doesn't lose her footing.

"It's 3089," he says absently. They must be nearing the source of the breach. Exposure to the elements has taken its toll on the fragile electrical systems powering the tunnel. He frowns up at the flickering tract lighting, the anaemic fluorescent glow growing darker and more intermittent further ahead. "We're nearing the end of the First Great and Bountiful Human Empire," he says.

Donna's nose wrinkles slightly at that. "How many Great and Bountiful Human Empires have there been?" she asks.

"Four," he says.

Donna shivers in the steadily increasing cold. "Why so many?" she asks.

"Walk on this side of me," the Doctor tells her, tightening his grip on her hand as she carefully picks her way around to his other side where he can shield her from the brunt of the knifelike wind with his body and the curving tunnel wall next to her.

He reaches into his pocket for the torch, illuminating the path ahead of them where the lighting has failed completely. "You know humans," he says mildly, "always blundering in before they've had a proper look round the place. There were quite a number of alien races that didn't take too kindly to having their space invaded by barbarians."

"You make it sound as if humans set out to conquer them," Donna says.

The Doctor shrugs. "Well, _you're_ the one that compared the human race to a virus remember? Just look at what they did to the Ood."

"Oi watch it Spaceman," Donna says tartly, "I'm sure the Time Lords had plenty of skeletons rattling around their closets in their day, and anyway there are bound to be mistakes on _both_ sides when you're first starting out."

The wind increases in intensity, screaming down the tunnel in a maelstrom of gritty snow and ice pellets. The Doctor turns his head slightly to avoid taking it full blast in the face.

"True enough I suppose," he says, briefly shutting his eyes against a particularly powerful gust, "but lessons were slow to be learned. The _First_ Empire ended in a war between the humans and pretty much every other race in the surrounding five galaxies."

"So there's a war waging somewhere out there?" Donna asks, shielding her face against his shoulder as the wind wails past.

"Nothing but a few frontier skirmishes by now I'd imagine," the Doctor reassures her, "the Empire is more or less in its death throes. Human refugees scattered throughout the known universe."

"Is that what this place is?" Donna asks, "some sort of refugee camp?"

"Possibly," the Doctor says, squinting into the thickening darkness ahead of them, "wars consume resources. Ideally you'd want to settle somewhere that had enough natural resources to replace the ones you'd lost. I suppose it's possible they came here to mine some new kind of energy source."

"But you don't think they did," Donna says thoughtfully.

She's getting to know him far too well. "I think, I haven't seen any evidence of actual mining beyond the carving of these tunnels, no," he says, one side of his mouth quirking into a little half-smile, "and there's really nothing more to this planet than a frozen cocktail of poison gasses anyway."

"So why come to a planet so clearly inhospitable to humans if there's nothing worth coming for in the first place?" Donna asks.

"Well that's the question, isn't it," the Doctor murmurs, thoughtfully chewing his bottom lip when the torch beam falls on a partial cave-in obscuring the tunnel just up ahead.

"Stay here," he tells Donna. "Just for a second," he says when she starts to protest. "I'd prefer to know if the ceiling's about to come down on our heads before going any further."

"Would that stop you?" Donna asks, her mouth quirking into a wry smile.

He pulls a face and strides after the torch beam, Donna's soft chuckle following him into the darkness.

Boulder sized chunks of ice block part of the path, but a narrow passageway remains at one end beside the intact cavern wall. Wind and swirling ice pellets howl through the spaces between the broken ice boulders like tiny white daggers. The Doctor skims the torch beam all along the edges of the cave-in, trying to determine what caused it. He wedges the torch between his teeth and climbs onto a broken outcropping, squeezing through the opening into the narrow corridor winding through the wall of broken ice.

Sooty grey dust hangs suspended in the thin air, coating his clothing with a layer of grime. He pulls a face, spitting the torch into his open hand and smearing a bit of the dust onto his bare fingertips before tentatively licking a tiny amount onto his tongue.

"Carbon," he mutters, grimacing a bit as he spits the charred dust from his mouth.

"Is this why they called for help?" Donna asks, stood directly behind him at the mouth of the narrow passageway. "They were trapped in a cave-in?"

The Doctor rounds on her. "I thought I told you to stay put," he snaps anxiously.

"Just for a second, you said," she says, scowling back at him, "and when you didn't immediately turn round and start pelting back up the tunnel towards me, I figured it was safe."

The Doctor frowns slightly at that. Getting to know him _far_ too well. "Fine," he mutters, "just stay close."

"Haven't got much choice, have I," Donna says, taking his hand and squeezing past the jutting crag of ice partially blocking the entry to the claustrophobic path.

"They weren't trapped," the Doctor says, illuminating a large metal door clearly visible at the far end of the tunnel with the torch beam, "clear path to the exit, see?"

"Well, maybe there's another cave-in behind it," Donna says with a shrug.

"I doubt it," the Doctor says, pulling a face, "I can't even find a clear reason for this one."

"How do you mean?" Donna asks, her brow knitting in confusion.

The Doctor bends slightly, the torch beam trained on a gap in the broken ice wall beside them. "What do you see?" he asks.

Donna tilts her head and squints into the dimness. Icy wind stirs up sooty whirlwinds of carbon dust that ruffle the fleece lining on the hood of her coat. "A great big hole," she says, flatly.

"Precisely," the Doctor says, "and look at all the debris laying on the ground on the _outside_ of the rupture."

"So what," Donna says, shaking her head.

"So the wall didn't cave _in_ Donna," the Doctor explains, "it blew _out_ and the sudden instability made the rest of the tunnel cave in behind it, but not all the way. _This_ wall held," he says, indicating the curving tunnel wall at their backs, "which means that structural integrity wasn't the issue. This collapse didn't just spontaneously happen. It had help."

"Wait, hang on a minute," Donna says. "Are you saying that they, that the people here intentionally caused this?"

"It's a possibility," the Doctor says, that vague feeling of uneasiness abruptly returning to claw at his stomach.

"But, why?" Donna asks. "Why would they intentionally try to trap themselves in a cave-in and then set a distress signal calling for help? It doesn't make sense."

"No," the Doctor agrees, "it doesn't."

He eyes the suddenly ominous looking door at the far end of the narrow passageway thoughtfully. "Come on," he says, taking Donna's hand as they continue to pick their way over the fragmented chunks of ice laying at their feet.

The control panel next to the door is frozen. The Doctor frowns at it, brushing away the permafrost coating with his gloves. "Hold this," he tells Donna, handing her the torch, then grabbing the sonic from his pocket.

Donna illuminates the panel while he pulses the sonic along its edges, popping the panel from its housing and exposing the wires inside. "A little more light," he says, slipping on his glasses.

Donna steps closer, her shoulder brushing his in the confined space. The Doctor smiles slightly as he works on bringing the ice covered mechanism back to life. How lovely she looks in the flickering light he thinks, her skin luminous despite the layer of grime coating it and her eyes shining like a stormy ocean.

"Eyes on your work, Spaceman," she says catching him looking, a playful smile tugging at her lips.

The Doctor's smile blossoms into a grin. "I was just calculating my chances," he murmurs thoughtfully, his attention returning to the mechanism in his hands.

"Chances?" Donna asks.

"Of getting lucky tonight," he says, waggling his eyebrows suggestively at her.

Donna rolls her eyes, though she doesn't try to hide the smile still tugging at her lips. "Honestly, you've got such a one track mind," she says.

"Not true," the Doctor says, wryly, "You of all people should know by now that I'm an extremely talented multitasker."

As if illustrating his point, the control panel flickers back to life in his hands.

"Show off," Donna mutters dryly.

He snaps the panel back into its housing flush against the tunnel wall. The worn number keys on the keypad are full of carbon dust and glow from within with a pale grimy light. He changes a setting on the sonic and points it at the panel, unlocking the door with a series of electronic beeps.

The door creaks and shudders, slowly sliding up into the ceiling on corroded steel tracks that are frozen and rusty from disuse. He glances at Donna, all traces of humour gone from her face as she stares into the darkness beyond the threshold. He frowns slightly, thinking he must be imagining the soft scrape of footsteps against the frozen earth when something roughly human-shaped suddenly lunges out of the darkness and crashes into him.

Donna shrieks, dropping the torch and flinching backwards. The Doctor blinks in the sudden darkness, going down under the unexpectedly rigid weight. Freeze dried flesh scrapes his face and he blindly pushes it away before scrambling to his feet again almost immediately.

"Well that was… unexpected," he grunts, scooping the torch up into his hand. Donna stands hyperventilating beside him, her hand pressed to her chest as she stares at the ice encrusted body laying rigidly at their feet.

"All right?" the Doctor asks her and she nods, her hand moving to her belly as she swallows convulsively. "Are you sure?" he asks, his brow furrowing slightly in concern.

Donna sighs, her breathing calming somewhat. "Premature labour from a fright only happens in the movies," she says, wrinkling her nose at him.

"Actually, it can be brought on by increased-" _stress_ , he's about to say, but the look on her face makes him think better of it, "-never mind," he says instead.

The body laying at their feet is human and completely frozen, like a side of beef hanging in a meat locker. The Doctor frowns thoughtfully at it, kneeling down to get a closer look at the crystallised flesh.

"What? Was it...he, just propped up in the doorway like a scarecrow?" Donna asks, nervously licking her cracked lips.

"Seems like it," the Doctor murmurs. He tilts the frozen corpse's head to reveal a massive hole at its temple. Red stained ice crystals track a trail of frozen blood down its rigid face and chest.

"Is that…?" Donna hesitantly asks.

"Gun shot wound," the Doctor says simply, "self inflicted."

"How can you tell that?"

"By the angle mostly," he says, "also…" he lifts the corpse's cold dead arm to reveal an old fashioned pistol still curled in its frozen fingers.

Donna shudders. "Did they go mad, do you think?" she asks, her tone subdued.

The Doctor doesn't answer. He stands and takes her hand, Donna's fingers curling tightly around his inside her mitten. He gives her hand a reassuring squeeze, raising the torch to pierce the gloom beyond the doorway's threshold. Several pod-like containers stand just inside like permafrost covered monoliths.

"What are they?" Donna asks, as they step into the carved chamber.

"Stasis pods of some kind," the Doctor says, squinting at the murky control panel on the side of one of the devices. "They appear to be cobbled together from bits of leftover equipment. Quite ingenious really," he says with no small amount of admiration for the architect behind this particular bit of homespun innovation.

"Are they still working?" Donna asks, cautiously tapping one of the crusted pods, bits of ice falling away at her touch.

"No," the Doctor says, pulling open the nearest pod door with ease. Donna leans against him as he shines the torch beam into the seemingly empty interior.

"What is that?" she asks, the light revealing a small pile of some sort of frozen organic material at the bottom of the pod. "It looks like… like, beef jerky," she says swallowing distastefully.

The Doctor grimaces slightly at that, reluctant to let on just how on the nose she may be. He opts to say nothing instead, moving further into the gloomy chamber. For some reason, it's drawing power from a source separate from the rest of the base, or it would be if the power were working.

"Ah-ha!" he exclaims, when the torch beam strays across a second computer console even larger than the first. He drops to his knees, removing a frozen access panel at the base of the unit. Ice crunches underfoot as Donna comes up behind him, squinting thoughtfully over his shoulder.

Some deft rewiring and he manages to coax the frozen mainframe back to life. He reestablishes the power and the blackened tunnel chamber is suddenly glowing eerily with luminescent UV light. He replaces the panel and stands, staring thoughtfully at the low hanging fluorescent lamps illuminating ice encrusted lab tables with various bits of scientific equipment strewn upon them.

"I thought you said this was supposed to be a central living space," Donna murmurs, her fingers spreading protectively over her belly as she eyes a sputtering cold storage unit with the word "Biohazard" stamped in bold red letters across it. "Is it even safe for us to be in here?"

"The sonic has a proximity alarm built in," the Doctor reassures her from the console, his fingers flying over the keyboard, "it would have alerted us to any airborne toxins or radiation in the area."

"Right, so we're not about to melt into bubbling puddles of goo," Donna says a bit hysterically, "good to know." She swallows, watching him for a moment as he slips on his glasses to squint at the jittery view screen overhead. "Can you even make sense of any of that," she asks, "it just looks like gibberish to me."

"Some," he says, skimming through the corrupted database files faster than any human being could. "Nothing particularly useful so far, just personal logs. Funny how you lot are all so obsessed with recording every moment of your lives no matter how insignificant. Just look at your _Facebook_ updates. Sat on the sofa. Sat on the sofa eating ice cream. Sat on the sofa eating ice cream, watching _Glee_. It's as if it's hardwired into your… ah!" he cries suddenly. "This looks promising," he says opening a folder labeled _Project Kafka_ , his eyes moving rapidly over the lines of data flying across the console monitor.

"More interesting than us boring little humans," Donna says sarcastically.

"I never said _you_ were boring," the Doctor says absently, most of his mind occupied with retrieving and restoring the contents of the degraded folder.

"No," Donna says tartly, "just my entire species. You're not exactly Graham Norton yourself you know. I seem to recall the main topic of conversation at the breakfast table this morning having something to do with spanners."

"Uh-oh," the Doctor whispers.

"What uh-oh?" Donna asks, her annoyance instantly forgotten in the face of his sudden apprehension. "Doctor? Uh-oh what?"

He swallows, his mouth suddenly dry. Donna's voice is drowned out by the pounding of his own hearts in his ears as he reads the restored contents of the folder and grows increasingly horrified by what he sees.

"Why come to a planet so clearly inhospitable to humans if there's nothing worth coming for in the first place?" he murmurs numbly, repeating Donna's earlier question as the pieces suddenly fall into place,"because you don't want anyone following and discovering what you're really up to."

"I don't…" Donna stammers.

"This isn't a refugee camp," he tells Donna, his tone somewhere between cold fury and outright panic, "it's a research base."

"What sort of-"

Then they both hear it, a loud chittering whine like a forest full of bush-crickets on a late summer's day. The Doctor blanches, his mind momentarily reeling as his eyes fall on Donna's suddenly pale face.

"What the hell was that?!" she cries.

"We have to go," he says brusquely, grabbing her hand.

"But, what about-"

"We have to go now," he snaps anxiously. "Right now!"

But it's already too late.

They turn to find a handful of inky black human sized insects blocking the exit, their long narrow bodies clinging to the sides of the doorway, hugging the rough hewn walls and ceiling as they slip into the room like a nest of giant cockroaches.

"Oh my God," Donna gasps breathlessly, fear robbing her of her voice.

The Doctor slowly pushes her behind him, placing his body between hers and the advancing horde. This is his fault. They'd gone dormant in the extreme cold until he'd reestablished the environmental systems and unwittingly revived them, exposing Donna and the baby to serious danger in the process.

"Did those things kill the research team?" Donna asks, her quavering voice barely above a whisper as they slowly back away.

The Doctor's arm curves around her back as he eyes the giant whining creatures skittering towards them, their hard black skins all but invisible in the murky darkness of the tunnels but glowing with an eerie blue bioluminescence inside the laboratory chamber.

"Those things _are_ the research team," he murmurs back grimly.

TBC


	2. Chapter 2

"Wh… what?" Donna gasps. "How can that be?"

The Doctor isn't listening. He reaches into his pocket for the sonic, his eyes glued to the advancing insect horde as he slowly draws the device out and slides a seldom used switch to a setting he's only used twice before, the maximum disassembly setting.

He risks a quick glance at the sputtering environmental converters above their heads, frost covered metal boxes with icy grates nestled between the rows of flickering UV lights. If he takes one of them out, it would set up a chain reaction throughout the base. The tentative mix of heat and oxygen will dissipate as the condensers fail one by one and the planet's poisonous atmosphere once again takes over.

If he's very lucky, it'll force the creatures back into hibernation. Of course that would also mean no oxygen for him to breathe, but the portable regulator Donna's wearing should last for several hours yet. She and the baby will be safe, which is all he really cares about. Although _safe_ is a relative term he supposes when being stalked by a horde of giant insects.

He frowns slightly at the thought, his eyes returning to the skittering hybrids as he slowly draws in several foul tasting breaths, building up his oxygen reserves before the condensers go offline and his body reverts to respiratory bypass to survive.

"When I tell you to run," he whispers into Donna's ear, as they pull up short against an icy lab table, "we run, and we don't look back until we reach the TARDIS."

"We're…" Donna gasps fearfully, "we're just going to leave?" She swallows, licking her lips as if nauseated, "but they were human once. Isn't this the moment when you usually try to reason with them? Offer them your help?"

"They're beyond help Donna," he says grimly, "beyond reason. It was already far too late for that by the time they decided to infect themselves."

"Infect themselves with what?" Donna asks, trembling behind him as the creatures advance.

"A retro-virus," the Doctor says, holding the sonic out like a beacon before him, waiting for just the right moment to use it. "They were attempting to improve on the human condition by augmenting it with a mixture of Terran and alien insect DNA."

"You have got to be kidding me," Donna gasps, "who _does_ that?"

"Someone desperate to win a war," the Doctor says coldly, his thoughts briefly turning to his own people and what they'd nearly done in the name of winning theirs."They were attempting to genetically engineer the ultimate soldier," he says, "only they got more than they bargained for. The virus they created didn't enhance their humanity, it stole it. It spread from one colonist to the next like wildfire, overwriting their DNA into something mindless. A living extension of the virus itself," he says, indicating the infected research team with a tilt of his chin, "a walking virus with just one single unwavering purpose; self-replication."

"The stasis pods," Donna murmurs, her pale face lighting with sudden understanding, and the Doctor nods.

"Built to contain the infected while they worked on a cure. A cure they never found apparently."

"Then that... stuff inside..."

"Human," the Doctor says with a grimace, "like a snake, shrugging off its skin."

"Oh my God," Donna nearly gags, her hand covering her mouth, "but… but I don't understand," she murmurs, her face pale with shock, "they called for help."

"No," the Doctor says. "They didn't."

He aims the sonic at the oxygen converter directly over their heads and activates it suddenly, unleashing an unholy wall of sound like the roar of a thousand jet engines echoing back at them through the tunnels. Donna yelps, her hands flying to her ears, but the Doctor just stands his ground, gritting his teeth as every connection holding the converter in place abruptly comes undone and it explodes in a shower of sparks, taking a good portion of the rough hewn ceiling with it.

"Run!" he cries, taking Donna's hand and heading for the doorway amid a shower of falling ice chunks and insect hybrids.

"What do you mean, they didn't," she gasps as they quickly wend their way back through the partially obstructed tunnel, "we answered their distress signal didn't we?"

"It wasn't a distress signal," the Doctor says, proud of her for needing an answer to the question, but slightly exasperated that she's asking it _now_ , "it was a warning beacon. Over the years the accompanying message to stay away became increasingly garbled, until finally only the beacon remained."

"And I insisted you answer it," Donna says, contritely.

"You couldn't have known," the Doctor says, glancing back over his shoulder at the angry insect hybrids just beginning to emerge from the doorway at the other end of the tunnel. He'd timed the explosion to go off just as the majority of them had reached the converter, but hadn't counted on their ability to recover quite this quickly.

"Come on," he urges Donna, his fingers curling tightly around her wool encased hand as he helps her past the icy outcropping at the mouth of the cave-in. A whining insect drone mingles with the roaring wind echoing through the tunnel and she blanches. "Don't look back," he says, "just run."

They pelt back up the permafrost coated tunnel as quickly as they can. Lights flicker and fade into darkness as the environmental systems grind to a halt and the freezing wind tugs at their backs with icy fingers. The whine of a dozen giant hybrid insects fills their ears and Donna stumbles, her knees going weak. The Doctor grimaces, wrapping his arm around her shoulder and forcing her to keep moving forward.

"How did it spread," she gasps, tears seeping from her eyes from fright or hormones or possibly just the cold, "the virus. You said it spread like wildfire. _How_ did it?"

But before he can form the words, they're suddenly struck from behind. A hard black body slams into the Doctor and he sprawls onto his stomach, Donna tumbling from his grasp. He struggles, scrabbling at the slippery ice in the growing darkness trying to regain his feet. Reticulated black limbs covered in stiff bristly hairs pierce the ice like grappling hooks around him and he tenses defiantly, struggling to lift his head and free himself of the crushing weight.

His eyes fall on Donna's crumpled figure in the dimness, surrounded by undulating insectoid bodies, her brilliant red hair like a silken waterfall spilling from the confines of her tattered hood.

"Donna!" he cries, his hearts leaping into his throat when she doesn't respond.

The hybrid insect pinning him slices through his anorak like butter, rending the tattered pieces from his body with dripping black claws. Through sheer force of will, the Doctor manages to climb onto his hands and knees and start crawling towards Donna's motionless body. The quivering creature yanks him back, the Doctor's outstretched fingers raking long trails in the frost slicked ground as he groans in frustration.

"Do you _mi_..." he starts to growl before something long and sharp pierces him between the shoulder blades and the breath abruptly goes out of him.

Burning venom spreads like hot magma pulsing outward from the wound, and he tries to scream, his body trembling like a butterfly caught on the head of a pin. Every nerve ending erupts in hot liquid pain and the scream dissolves into a gurgling whimper, his senses shattering as his mouth fills with something bitter and his vision starts to crumble around the edges.

He's only vaguely aware of the creature releasing him, his body convulsing once as it withdraws its stinger and he falls, twitching feebly to the icy ground. His failing eyes find Donna's unmoving form in the darkness. _I'm sorry. I'm so sorry_ , he briefly thinks, before all thoughts vanish in a burning haze of pain. His chin sinks to the frosty ground and blessed darkness claims him.

"Are you awake?" Donna whispers in the darkness, the two of them wrapped up in bed together. The Doctor's arm is draped over her hip as she spoons naked against him.

"Yes," he says simply and she rolls over onto her back, gazing up at him as he props himself up on one elbow to look at her. His eyes play over the languid curves of her body, lingering for a moment on her shapely breasts.

"What are you thinking about?" she asks, reaching up to caress his stubble covered cheek, her thumb lightly tracing the outline of his lips.

"You, mostly," he says, taking her hand and planting a feathery soft kiss on her palm.

"Mostly?" she asks, one eyebrow cocking slightly when his smile falters almost imperceptibly. "It's been two weeks since we found out and you haven't said a word about it since. It's not like flu you know. There's no such thing as a temporary case of pregnant."

His mouth quirks slightly at that. "I know," he says softly.

"I thought you were happy," she says.

"I was," he says firmly. "I am. It's just…" he breaks off with a sigh and thoughtfully scratches the back of his head. "It's been a long time since I became a father the old-fashioned way Donna," he says, his smile turning wan, "since before the time war. I'm not sure I even remember how."

"You do," Donna tells him, her tone reassuring. "I saw how you were with Jenny in the end. You would've been a good father to her."

He frowns, his forehead puckering as he rolls onto his back and stares up at the roundel covered ceiling. "Yes, and look at how well that turned out for her," he says flatly.

"You can't blame yourself for what happened," Donna says, turning onto her side to rest her head against his chest, her silky hair tickling his skin.

"No?" he asks, his eyes flickering to her face. "Who then?"

"Umm, how about the nutter holding the gun," Donna says flatly and though her argument is technically true, it does little to ease the Doctor's guilty conscience.

"Don't borrow trouble my mum always says," Donna tells him, her hand sliding up his bare chest to cover one of his hearts. "people still have free will you know. You can't hold yourself responsible for every bad decision they make in your presence."

"No," he agrees somewhat reluctantly, "but I can hold myself responsible for the ones they make as a direct consequence of my actions. You heard what Davros said about me. I take ordinary people and I fashion them into weapons."

Donna rolls her eyes. "Oh right, so we're listening to Davros now, because he was, you know, such a picture of mental health," she mutters sarcastically.

"Just because he was mad doesn't mean he wasn't speaking the truth, Donna," the Doctor tells her.

"It doesn't mean he _was_ either," Donna insists.

"You're the one who accused me of turning Martha into a soldier remember," he says.

"Well, I didn't mean it like that," she snaps.

"You weren't wrong," he says, shame colouring his cheeks, "and neither was Martha. I'm like fire. I burned her and I burned you, I couldn't live with myself if I wound up burning the baby as well."

"That's not what you do," Donna says, her storm coloured eyes locking with his. "You don't burn people. You inspire them to find the best in themselves just by believing that they can."

"I inspire them to lay down their lives," he says bitterly.

"Maybe that's just human nature," Donna says, "maybe if you inspire us to overcome our inherent weaknesses, then what remains is selfless."

"I never wanted that sort of responsibility."

"Really," Donna says flatly, "because from where I'm sat, it kind of looks like you do."

"What's that supposed to mean?" he asks sharply.

She frowns at him and abruptly sits up. "It means you're not God," she says, "so stop trying to act like it. Time Lords are so much bigger than the rest of us is that it? Your big fat heads are far too complex for our tiny human brains to understand, well in case you hadn't noticed, I didn't fall pregnant and suddenly forget who you are you know. It isn't as if I expected you to give up traveling or demanded that you abandon the TARDIS for a country house in Heathfield Court." She blinks and swallows suddenly. "Now if you'll excuse me, apparently I sat up too quickly and have to go throw up now," she says. "Feel free to take as much blame for _this_ particular consequence as you like."

With that she bolts from the bed, the silken sheets falling away from her naked body as she runs for the bathroom and slams the door shut behind her. The Doctor sits up, grimacing slightly at the sounds of retching coming from the closed room. He plucks his pyjama bottoms from the floor where they lay in a puddle of hastily removed clothing by the side of the bed and shrugs them on as the toilet flushes.

He stands there for a moment, watching the still closed door expectantly. Five minutes later Donna still hasn't emerged, though the room has lapsed into silence. He gives the doorknob an experimental turn and finds the door unlocked. He pushes it open to find her perched on the toilet seat, slowly sipping water from a paper cup.

He leans against the doorframe, watching her in silence as she intentionally avoids making eye contact with him, her renaissance curves already beginning to blossom with the first signs of impending motherhood. She's never looked more beautiful he thinks, her luminous skin glowing with the promise of the brand new life growing inside of her.

"Is that what you wanted," he asks softly, "a country house in Heathfield Court?"

Donna frowns into her flower embossed cup as if the water inside has suddenly turned bitter, "I could have had that with Shaun," she says flatly. "You came back and I left him for you." She looks up at him suddenly. "What does that tell you?"

One side of the Doctor's mouth quirks into a wan smile. "That I really don't deserve you," he says.

Donna nearly smiles at that. "So my mum keeps telling me," she says.

He walks into the room and Donna impulsively threads her fingers through his as he takes a seat beside her on the edge of the bathtub.

"For the record, I would never try to buy my own happiness at the expense of yours," she tells him.

"I know," he says simply, his thumb tracing light trails over the back of her hand.

"I never expected you to change for me," she says.

His mouth quirks slightly at that. "Did I ever tell you why I started traveling Donna?" he suddenly asks her.

"I…" Donna blinks, slightly thrown by the unexpected question. "I suppose I always just assumed it had something to do with your adolescent addiction to adrenaline."

"No," he says, one eyebrow quirking wryly, "that wasn't it. It was because I needed to find something that the Time Lords lost a long time ago."

"What like buried treasure, you mean?" Donna asks, and he can practically see the moment when she turns him into Indiana Jones inside her head.

"Ourselves," he says, smiling a little despite himself, "We were just like human beings once you know, in the beginning. So full of passion and conviction, but then we evolved. We harnessed the vortex and it changed us..."

"It stagnated you," Donna guesses and the Doctor nods.

"Somewhere along the line we traded our humanity for, I don't know. Knowledge. Power. Arrogance maybe. After a while, it was all we were. There was nothing else."

"But, _you_ were different," Donna says.

"No Donna," the Doctor says ruefully, "that's just the point. I wasn't. Not really." His fingers tighten around hers. "You said you never expected me to change," he says softly, "but you have changed me. All of you have. All the human beings I've traveled with through all those regenerations helped me rediscover the humanity I'd lost. I should have realised it would just be a matter of time before the change would be significant enough to…" he breaks off, his eyes straying to her thickening waistline.

"Make the impossible, possible," Donna murmurs thoughtfully, her fingers spreading over her belly.

"I lost everything I had in the blink of an eye," the Doctor says, his fingers covering hers, "everything I cared about. Now I'm on the verge of building something just as good with you and I'm…" he breaks off, his voice cracking as he swallows past the sudden lump in his throat, "I'm…terrified that it will be ripped away from me and I'll end up losing myself all over again."

"I'd never let that happen Spaceman," Donna tells him emphatically, her hand disengaging from his to caress his face. "The stakes are higher now it's true," she says softly, her fingers raking soothing trails through his hair. The Doctor closes his eyes, his forehead falling against hers. "It's not just you anymore," she murmurs. "You've got more to lose now, but that just means you've got more to live for as well. We both do. Isn't the chance of holding onto that worth the risk?"

The Doctor's mouth quirks into a fleeting smile and he kisses her suddenly, Donna's soft lips parting beneath his. She tastes of mint mouthwash and cherry lip balm and human kindness.

"I'll take that as a yes," she gasps, throwing her arms around his neck to answer his kiss with one of her own.

He hears something. The wind screams in his ears, settling into his bones with a numbing ache and he can hear a soft keening somewhere in the background, like a wounded animal whimpering in pain. He opens his eyes, blinking spots. A rasping groan echoes back at him from shadowy walls he can't see through the darkness. It takes him a moment to realise the sound is coming from him, his throat aching and raw with the strain of it. Tiny frozen daggers pelt him in the face, rifling through his hair like talons and he stops groaning, his mouth full of something viscous and bitter. He gags, clutching at the frost covered earth with numb fingertips. He lurches onto his side to spew something blacker than the pitch black darkness all around him onto the ground.

The Doctor lays there trembling for a moment, the icy wind cutting through him like a knife. Something that feels like a hot coal is slowly burning its way through his back between his shoulder blades, burrowing into his chest like a hot drill. He blinks, his eyes blurry and sore. He flops back onto his back, shuddering with the sudden jolt of pain that passes through him like a lighting bolt. He swallows and grits his teeth against the bile rising in the back of his throat. Reaching into his overall pocket with grimy trembling fingertips, he pulls out something that looks like a large multifaceted crystal doorknob.

He presses a switch at the base of the crystal and a bright white beam of light springs from it, increasing in intensity until he's forced to avert his eyes. The light continues to flare until the darkness is banished, then fades back to a more comfortable level. He groans, blinking sunspots, startling suddenly when he abruptly notices the giant hybrid insects hanging in a tangled clump not three feet above his head.

He swallows, warily turning his head to squint at something blurry and orange laying in a crumpled heap near the mouth of the chamber. At first he thinks it's the remains of his anorak, until he spies the matted ginger curls tumbling from the hood.

"Donna!" he gasps, both of his hearts immediately pounding in his ears. He lurches onto his hands and knees, blinking stars as his head starts to swim. The not quite immobilised creatures covering the chamber's low-hanging ceiling twitch feebly in the gradually altering atmosphere as he crawls over to her.

"DonnaDonnaDonna," he babbles hoarsely, the words tumbling from his mouth in a panic as he eyes the dark blood seeping sluggishly from a gash at her scalp. It slides in a thin rivulet down the virtual mask still covering her face to the permafrost covered ground. The Doctor swallows, his hearts hammering in his ears as his trembling fingers check the pulse at her neck.

He nearly collapses with relief when he locates the reassuring rhythm of her slightly elevated heartbeat. He examines the wound at her scalp, brushing her sunset hair back to reveal a shallow gash and a bruise discolouring her brow, bloody, but thankfully not life-threatening.

He shudders, nearly breaking down, blinking tears as his eyes close. His trembling fingers spread to caress Donna's face as his mind reaches out to check on the baby. He's only able to manage the briefest moment of contact before losing his concentration, his misfiring nerve endings smouldering like burning embers beneath his skin, but it's enough to establish that the baby too is unharmed.

The Doctor sags, his grubby fingertips scraping the icy ground. He blinks, shaking his head, his senses fading in and out like painful strobe lights, blurring and sharpening and blurring again as the retro-virus begins to overwrite his DNA with its own.

He glances up at the quivering hybrids hanging over his head, their brittle shining bodies periodically convulsing in the diminishing atmosphere. He wonders how long they'd managed to hold onto their humanity before losing themselves completely to it.

Donna groans and the Doctor leans over her. "Easy," he murmurs softly, her eyelids fluttering for a moment before her stormy blue-green eyes open and focus somewhat sluggishly on his face.

"Is the baby all right?" she murmurs, her words a bit slurred as she weakly grips the collar of his pullover.

"The baby's fine," the Doctor reassures her, his grubby fingers closing over her mitten covered hand, "and so are you." He tries to smile as he helps her sit up, but the knowledge that this will likely be their final moment together keeps it from forming on his lips.

They share a brief embrace, Donna's gaze shifting from his face to the hybrid covered ceiling above their heads. To her credit, she doesn't scream, though her complexion visibly pales. "God," she breathes, her voice barely above a whisper, "are they dead?"

"Dormant," the Doctor murmurs back, "or very nearly," he says, shaking his head again to try and clear his vision. "The environmental systems have mostly failed, forcing them into hibernation to survive."

"How long can they stay like that?" Donna asks, studying the Doctor's face with some concern.

He swallows, his head beginning to throb as the virus races through his bloodstream, raising his blood pressure and constricting his blood vessels. "As long as it takes," he says, queasily licking his lips.

Donna swallows, warily eyeing the rough hewn chamber walls. "What, is this some sort of nest?" she asks.

"So it would seem," the Doctor nods, _or an incubation chamber_ he thinks, though he doesn't say it out loud.

The mouth of the chamber fades into utter blackness beyond the perimeter of the still softly glowing crystal. Donna eyes the emptiness apprehensively. "Do you have any idea where we are?" she asks.

"Not a clue actually," he says, his spatial sense blurring almost as badly as his vision.

"But, you _can_ still find your way back to the TARDIS right?" she asks him.

The Doctor slowly shakes his head. "I'm not going back to the TARDIS Donna," he says, his voice cracking hoarsely on the words.

"Don't be an idiot," Donna says, her casual tone belying the sudden look of panic in her eyes. "Of course you're going back to the TARDIS."

"I can't leave Donna," the Doctor insists quietly, "I've been infected."

"No, that's… no..," Donna stammers, shaking her head, "but you're... you're immune right?" Her grip on the collar of his pullover tightens in desperation as her eyes fill with tears. "Please tell me you're immune!"

The Doctor shudders, his raw nerve endings erupting in a wave of exploding capillaries just beneath the surface of his skin. Donna's eyes widen in horror at the spontaneous bruises springing out all over his face.

"Don't think so," the Doctor says, trying to sound wry and failing.

"Oh my God," Donna whimpers. "No, but you can... you can find a cure," she insists tearfully, her hands balling into fists against his chest.

"No…" he says softly.

"Yes, of course you can," Donna cries, her trembling fists impotently pounding him now, "If anyone can find a cure, it's you."

"No, Donna!" the Doctor snaps, grabbing her hands in growing exasperation. A flurry of activity ripples through the semi-comatose hybrids above their heads and he grimaces, waiting for them to stop moving completely before continuing. "Listen to me," he says, his tone more subdued, "we're running out of time. Take the crystal and find your way back to the TARDIS."

"I can't…" Donna sobs miserably against him, big sloppy tears rolling down her cheeks.

"Yes, you can," the Doctor says firmly, "just concentrate on the TARDIS and she'll lead you to her. Once you're safe on board, she'll activate Emergency Program One and take you back home to Chiswick."

Donna's eyes flash angrily through her tears. "While you do what exactly? Just stay here and join the horde?" she snaps tartly.

"No," he says, his lips pressed together in a grim line, "I'm going to finish what the last human left here was trying to do when he blew out that tunnel. I'm going to destroy the base."

" _That's_ your brilliant plan," Donna hisses, angrily swiping the tears from her eyes, "destroy the planet and kill yourself?"

"I've got no other choice Donna," the Doctor says, his entire body beginning to tremble with nerve imploding pain. "The virus was designed to adapt. That's what makes it so dangerous. Every time it replicates itself it incorporates the newest host's DNA into its viral matrix and it becomes stronger. Consuming a Time Lord would make it practically unstoppable. It would have Time Lord intelligence and the ability to regenerate. It would find a way to escape the confines of this planet and it would invade the universe like a black plague, spreading from planet to planet replicating itself until there was nothing left, but _it_."

"I don't care," Donna says defiantly. "I'm not leaving you here to die. Think of something else."

"Donna, please," he says, grimacing with pain, "we don't have time for this. If you lov-, care about me at all you'll do as I say and let the TARDIS take you home."

"Give me your hand," she demands and the Doctor blinks, momentarily confused.

"Donna," he grumbles, annoyed.

"Shut up," she snaps, "and give me your hand."

Reluctantly he lays his hand in hers palm up, his exposed finger tips swollen and waxy looking. She peels off his glove, then surprisingly unzips her anorak.

"Donna what are you..?"

"Shhh," she says, unfastening one of the Velcro braces holding up her overalls and lifting her pullover to expose a small portion of her swelling belly. She takes the Doctor's hand and lays it on her exposed skin, shivering slightly at its unexpected lack of warmth. He mumbles some sort of apology, but she just shushes him again and watches him with an expectant look on her face. That's when he feels it, three determined little thumps striking his hand in rapid succession.

"Was that a kick?" he asks, his throat constricting with a feeling he hasn't felt in so long, he's not even sure he can put a proper name to it.

"Yeah," Donna whispers, her own voice choked with emotion.

"When did this start?" he asks. So much time has passed since he's felt one of his own children moving beneath his hand, he'd literally forgotten what it felt like until this moment.

"It's a recent development," Donna says, tears beginning to seep from her eyes again. "That's your son," she tells him, her hand covering his. "and if you think I'm just going to let you roll over and die without even trying for a chance to see him grow up, you're crazy. So you come up with another plan Spaceman!" she cries, her voice rising sharply, "because I'm not leaving this place without you!"

"Growing…" the Doctor murmurs, his bleary eyes narrowing thoughtfully, "growing up..."

"What?" Donna asks hopefully, but he doesn't answer, because he'd thought that it had just been dumb luck that Donna hadn't been infected. He'd just assumed the creatures had mistaken her for dead when she'd been knocked unconscious, but what if there was more to it than that? What if they hadn't infected her, because they couldn't?

"Of course," he breathes and he could kick himself, because the answer has been right here staring him in the face the entire time.

"Of course what?" Donna asks. "You've thought of something," she says, "I can see it on your face."

"Maybe," the Doctor admits, "but it doesn't matter," he says shaking his head. He crawls back to the still glowing crystal, scooping it up with numb fingers.

"How can you say that?" Donna demands, hastily bundling herself back up against the bitter cold. "Of course it matters."

"It doesn't matter because it's too late Donna," he snaps, his patience wearing thinner the longer she argues with him. "I mean yes, maybe I could find a cure if I had a week and a team of geneticists working with me, but we haven't got anywhere near that sort of time," he says, slinking back towards her and dropping the crystal into her hand.

"So we leave now," Donna says, "we go back to the TARDIS and we find a place where they can help you."

"I can't leave," he insists.

"Why not?" Donna cries, clearly exasperated.

"Because it doesn't work that way!" he shouts back, his stomach cramping painfully. "I can't come back later, because I'm here now." He casts a wary glance at the fluttering clump of waning hybrids over their heads. "This base was inactive for over thirty years Donna," he says, "until I came along and brought the mainframe and environmental systems back online. A project like this would have gotten its start at the top. Even after all these years, it's possible this base is still being monitored by whoever sanctioned it. They may have already dispatched a ship to investigate. Don't you see, I can't leave as long as that possibility exists. I have to end it now, before someone comes along and inadvertently unleashes something devastating onto the universe." He groans, doubling over as burning pain radiates up from his abdomen, his back tensing with the intensity of it. "There's nowhere we could go that would be safe anyway," he says, gritting his teeth. " _I'm_ not safe," he gasps, tiny beads of cold sweat springing out all over his bruised skin.

"What about _Torchwood_?" Donna asks, helplessly wrapping her arms around him. "They spent all those centuries studying you."

"So they could figure out how to kill me," the Doctor gasps.

"My _point_ is they must know more about Time Lord physiology than anyone else," Donna says, pulling a face. "If anyone could help you, it would be them."

The Doctor frowns, though she's not wrong. It seems presumptuous to expect Martha and Jack's help after purposely avoiding them for so long.

"You were always going to have to face them sooner or later," Donna says, as if reading his thoughts.

He heaves a trembling sigh, his lips quirking sadly as he shakes his head. "There isn't time Donna," he says, "I need to get back to the research lab and overload the main computer. It's the only power source large enough to destroy the entire base."

"Don't computers just shut down if they overload?" Donna asks.

"Not if I override the safety protocols first," the Doctor grunts, blinking sweat from his bleary eyes, "the resulting arc flash should ignite the carbon particles suspended in the air and destroy the base." He licks his lips, swallowing bile as a wave of nausea passes through him. "It'll take some time for the feedback to build up," he says, somewhat breathlessly, "but not nearly enough to make it back to the TARDIS. I'm sorry Donna," he gasps, when she starts to protest, "but there's just no other way. Get back to the TARDIS and let her take you home."

"What if I bring her to you," Donna says suddenly. "You said it yourself, I'm getting pretty good at piloting her."

"Piloting maybe," the Doctor says flatly, "but you've never set coordinates before, and all the controls are in _Gallifreyan_.

"I'll muddle through," Donna says stubbornly. "At least let me try," she pleads, her blue-green eyes bright with unshed tears, "please…"

The Doctor caresses her cheek, his fingers numb and stiff with cold. _His_ Donna, so stubborn and opinionated and brilliant, like a force of nature. He has the overwhelming urge to tell her how much he loves her at this moment.

"All right," he says instead. He's only humouring her, but she doesn't need to know that. Once she's safe, the TARDIS will make sure she stays that way.

Donna throws her arms around his neck and clutches him to her as if her life depends on it, but the Doctor can't quite bring himself to return the hug.

"Take the crystal and get back to the TARDIS," he tells her.

"What about you?" she asks.

"I've got another torch," he says, his lips quirking fleetingly, "always carry a spare, that's my motto."

"Oh really," Donna says, "I thought it was run away really, really fast."

"That to," he says, "now go."

She crawls to the mouth of the chamber and quickly slips into the pitch black tunnel beyond it. She rises to her feet, clutching the warmly glowing crystal in her mitten clad hand like a beacon, closing her eyes for a moment to get her bearings.

"I've found her," she says after a moment, her eyes snapping open as if she can't quite believe it was that easy, "she's not far."

"Which way to the research lab?" the Doctor asks, his temporal and spatial senses winking in and out like flickering stars behind his eyelids.

Donna frowns. "How the hell am I supposed to… Oh," she says, blinking suddenly as the TARDIS presumably lays it out for her. "Wow. Better than GPS," she says, then points into the inky darkness over her shoulder. "Back that way about one hundred and fifty metres, then bare left for another fifty or so."

"Right," he says. He pulls a slim silver torch from his fleece lined pocket and follows Donna out into the tunnel. He swallows, slowly rising to his feet as Donna lingers beside him, her wool encased hand pressed flat against his heaving chest.

"Go," he gasps, giving her hand one final squeeze before they part.

"This isn't goodbye Spaceman," she says firmly, "just… just try not to do anything stupid before I get back," with that she turns and begins to make her way down the icy tunnel, the glowing light crystal bobbing in her hand as she carefully picks her way over the uneven ground.

"Been there, done that," the Doctor mutters crossly, before turning somewhat unsteadily and stumbling off in the opposite direction.

It takes longer than he'd anticipated to get back to the lab, his blurry vision hindered by murky shadows and his limbs stiff and aching with cold or with the virus, he can't really tell. By the time he reaches the slightly illuminated laboratory chamber, he's got the shakes so bad he can barely keep hold of the torch. Its roaming beam bounces around the room like a disco spotlight.

The motionless body of a hybrid glimmers beneath a jagged chunk of ice in the doorway. The Doctor frowns and steps over it, his knees going momentarily weak as more capillaries burst beneath his skin and he doubles over in pain, vomiting something that looks like used coffee grinds onto the frozen ground.

"Right, well that can't be good," he murmurs, dragging a trembling hand across his damp forehead.

He hears movement coming from behind him and anxiously spins around, the erratic torch beam playing over the edges of the empty doorframe. The Doctor scans the ground. The lifeless creature hasn't moved. It's still laying crushed beneath the sharp ice. His mind must be playing tricks on him.

He swallows and turns his attention to the sputtering computer console in the centre of the room. He drops to his knees in front of the access panel, grimacing in pain as he removes it with trembling fingers, trying to ignore the fact that his fingertips have gone all black and sticky as he trips the circuit breakers on the voltage suppressor clamps and removes them one by one from the flickering mainframe.

He drops the last one onto the frost covered ground and staggers to his feet, his aching fingers moving stiffly across the keyboard as he writes a simple self-replicating virus program designed to eat up memory and overload the computer's central core processor with vast amounts of useless information.

He frowns, squinting at the flickering monitor above his head as the last bits of code scroll across the screen when a chitinous black hand seizes him by the shoulder, its long sharp claws digging painfully into his tender flesh. The Doctor gasps, bruising painfully in the creature's iron grip. He struggles to tap the return key on the keyboard, trying to execute the virus even as the creature drags him away and flings him across the room.

He lands in a crumpled heap against a moulded steel table leg, the impact knocking the wind out of him as the whining hybrid slowly advances on him, its movements somewhat erratic in the oxygen starved atmosphere. It knows what he's trying to do, or rather the retro-virus does and has jump started a soldier drone to deal with the threat.

The Doctor grits his teeth and climbs to his feet, his own oxygen reserves nearly depleted. He quickly scans the lab table behind him for a defensive weapon of some kind. Everything on it is bolted down; and he lost the sonic when he lost his anorak.

He grimaces, slowly backing away and placing the permafrost coated table between himself and the erratically advancing creature. It hisses and flings itself at the table, landing on top of it to loom threateningly over the Doctor as he cowers against the tunnel wall. It lunges at him and the Doctor drops to his knees, rolling under the table and scrambling to his feet again as the thing bounces off the tunnel wall behind him.

Arm outstretched, the Doctor stabs the keyboard and instantly the monitor above his head begins to fill with line after line of endless scrolling data. The quivering hybrid screams, its formidable mandibles gnashing as the Doctor squares his shoulders and turns to face it.

"Yeah, I know," he says, the sputtering mainframe at his back already beginning to whine and spark with mounting feedback, "but you know what they say. Some days you're the windscreen. Some days you're the bug."

The thing unfurls itself, the chitinous carapace covering its back splitting into rudimentary wings. The Doctor closes his eyes, resigned to his fate. The TARDIS should have gotten Donna to safety by now and that's all he cares about really, though he does regret not kissing her when they didn't say goodbye back in the tunnel. He has other regrets too of course. Not living to see the birth of his son, or knowing his name. Ironic that, a Time Lord not knowing his own son's name, but mostly he regrets that one last kiss that he and Donna never shared.

The creature slams into him and the Doctor goes down hard, the cold hard ground rushing up to meet his burning back and knocking the wind out of him. Dripping mandibles hover inches from his face and the Doctor smiles, giddy from lack of oxygen. The mounting feedback overloading the computer's central processor mingles with the creature's enraged bush-cricket whine, reaching an oddly familiar crescendo as it goes in for the kill, its gnashing jaw headed straight for the Doctor's vulnerable throat.

He closes his eyes, bracing himself for the blow that somehow never comes. Instead, the creature rears back, its entire body convulsing for a moment before it falls to the ground in a stunned heap. A very determined looking Donna is stood over it holding the console room mallet in her hand. The creature collects itself, rising to meet the new threat and Donna swings the mallet in a wide arc like a cricket bat, delivering a wicked uppercut to the thing's face and crushing one of its protruding mandibles. It goes down in a twitching heap and Donna drops the mallet.

"Doctor!" she cries, her coarse wool mittens chafing his tender skin as she tugs at the sleeves of his pullover. "Doctor get up!"

The Doctor blinks, his vision disintegrating around the edges as he tries to focus on her face. Mounting feedback fills his aching head like a buzzing hornet's nest and he seems to have lost all control of his aching limbs.

"Doctor please!" Donna pleads, and he forces himself to move because she'll be caught in the blast if he doesn't.

She helps him to his feet, his knees instantly buckling. He goes down onto his hands and knees. The TARDIS, briefly flashes at the edge of his vision as his head swims. Donna falls to her knees beside him, urging him to keep moving, desperately tugging at his grubby clothes. The whining feedback reaches a critical pitch and the Doctor grits his teeth, struggling to his feet again. The stunned hybrid shakes off the effects of Donna's attack and staggers after them as they stumble towards the open TARDIS doors, the console room shining with an inviting amber glow and the promise of blessed oxygen.

They stumble over the threshold, the enraged hybrid snatching at the Doctor's collar with its viscous claws before the TARDIS doors fly shut with a resounding creak, locking the creature out. The creature rakes the blue wood and shrieks like an old time cinema monster. The Doctor stumbles onto his hands and knees, taking in great gulps of oxygen-rich air as Donna flies up the catwalk towards the console.

Suddenly a bright flash of light radiates through the door seams and the hybrid's buzzing shrieks abruptly cease in the wall rattling explosion that follows a few seconds later. Donna screams, falling to the floor as the TARDIS tumbles, caught in the shockwave. The Doctor struggles to his feet and stumbles up the catwalk. The TARDIS reels through the air as he grips the console, throwing levers and spinning dials until she slips into the vortex and her flight path levels out. He sets the coordinates for Cardiff 2010, then sinks to the floor, gasping for breath as he finally gives in to the pain, his entire body trembling with the intensity of it. Donna crawls over to him, wrapping her arms around him and hoping that the disorientated TARDIS is taking them where they need to go.


End file.
